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  • From: Richard Morris <webmaster@pfaf.org>
  • To: Permaculture Plant Database <pcplantdb@lists.ibiblio.org>
  • Subject: Re: [pcplantdb] Website - images
  • Date: Fri, 17 Dec 2004 11:55:00 +0000

John Schinnerer wrote:

Aloha,

I'll adjust the tracking a bit. Hmmm, smooth gradient from light to dark purple...BTW, does the purplish blue and green irk anyone?


I liked Chad's 3-D looking logo much better than the IMO cartoonish font in current one.

I can't say exactly how PNG works, though I believe the palette is larger, and its similar to GIF in approach.


PNG is the more sophisticated and "free" (e.g. international standards-group-developed public-domian) replacement for GIF (GIF algorithm is owned by Unisys or someone like that and royalties are legally due on software that incorporates it to produce GIF output).

I think the pattent has expired on gif or the LZW algorith which does the compression. Hence the

PNG is a "lossless" format, like GIF (JPEG is "lossy," that is, when saving as a JPEG, image data is discarded).

PNG supports both horizontal and vertical image data scans (GIF only one, horizontal I think) so depending on image it may give better compression. However being "lossless," on average it performs about the same as GIF in 8-bit mode.
In 24-bit mode it of course produces much larger image file sizes.

PNG supports both 8-bit and 24-bit color palettes and as Bear says stuff like...

... 256 levels of transparency.

I beleive older version of IE did not support transparancy very well.

And I believe alpha channel is in the spec also, though I think there's very little support for that even yet.

Plain 8-bit PNGs are reasonably well supported on more recent browsers.
Multiple levels of transparency are more iffy.

I'm fairly agnostic as to GIF/PNG how well PNG is suported by browsers is the only limiting factor.

Rich
--
Plants for a Future: 7000 useful plants
Web: http://www.pfaf.org/ same as http://www.comp.leeds.ac.uk/pfaf/
Post: 1 Lerryn View, Lerryn, Lostwithiel, Cornwall, PL22 0QJ
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